Final answer:
Alvin exhibited a rational behavior style by focusing on business-related topics during the group lunch.
Step-by-step explanation:
In this scenario, Alvin is exhibiting a rational behavior style. Rational behavior refers to making decisions and behaving in a manner that is logical, objective, and based on rational thinking. Alvin's focus on business-related topics during the group lunch suggests that he is being analytical and objective, considering the practical aspects of the conversation rather than getting caught up in personal or emotional aspects.